DC bias current flowing into the neutral point of power transformer will seriously affect the normal operation of AC power system. In this paper, exciting current, harmonic component of the excitation current, magneti...DC bias current flowing into the neutral point of power transformer will seriously affect the normal operation of AC power system. In this paper, exciting current, harmonic component of the excitation current, magnetic flux density and noise of transformer were analyzed when the transformer is in the no-load operation state based on field-circuit coupled method. Through the calculation and analysis, some reference bases are provided for design of transformer.展开更多
DC magnetic biasing problem,caused by the DC grounding electrode, threatened the safe operation of AC power grid. In this paper, the characteristics of the soil stratification near DC grounding electrode was researche...DC magnetic biasing problem,caused by the DC grounding electrode, threatened the safe operation of AC power grid. In this paper, the characteristics of the soil stratification near DC grounding electrode was researched. The AC-DC interconnected large-scale system model under the monopole operation mode was established. The earth surface potential and DC current distribution in various stations under the different surface thickness was calculated. Some useful conclusions are drawn from the analyzed results.展开更多
直流电流互感器(direct-current current transformers,DCCT)是高压直流输电系统中的重要测量设备。为保证其准确可靠,DCCT投运前和停电维护时需现场校准。对于电子式DCCT现场抗干扰及数字化同步两大关键问题,该文提出电子式DCCT的校准...直流电流互感器(direct-current current transformers,DCCT)是高压直流输电系统中的重要测量设备。为保证其准确可靠,DCCT投运前和停电维护时需现场校准。对于电子式DCCT现场抗干扰及数字化同步两大关键问题,该文提出电子式DCCT的校准方法并设计一套校准系统,主要包括直流电流源、作为标准器的磁调制式直流电流比较仪(DC current comparator,DCC)和具有光纤数字同步的电子式DCCT校验仪。重点对标准器和校验仪进行了现场抗干扰分析,对于标准器现场使用时可能遇到的母线偏心和邻近通流导体干扰情况进行仿真分析,优化磁屏蔽结构,研制了DCC样机,经中国计量科学研究院校准,该DCC不确定度为5×10-6,在此基础上进行了母线偏心和邻近导体影响测试,验证了优化的屏蔽结构能够有效抵御现场干扰;为检验校准系统,采用0.2级DCCT进行了校准测试,结果表明校准系统不确定度优于5×10-4。展开更多
文摘DC bias current flowing into the neutral point of power transformer will seriously affect the normal operation of AC power system. In this paper, exciting current, harmonic component of the excitation current, magnetic flux density and noise of transformer were analyzed when the transformer is in the no-load operation state based on field-circuit coupled method. Through the calculation and analysis, some reference bases are provided for design of transformer.
文摘DC magnetic biasing problem,caused by the DC grounding electrode, threatened the safe operation of AC power grid. In this paper, the characteristics of the soil stratification near DC grounding electrode was researched. The AC-DC interconnected large-scale system model under the monopole operation mode was established. The earth surface potential and DC current distribution in various stations under the different surface thickness was calculated. Some useful conclusions are drawn from the analyzed results.
文摘直流电流互感器(direct-current current transformers,DCCT)是高压直流输电系统中的重要测量设备。为保证其准确可靠,DCCT投运前和停电维护时需现场校准。对于电子式DCCT现场抗干扰及数字化同步两大关键问题,该文提出电子式DCCT的校准方法并设计一套校准系统,主要包括直流电流源、作为标准器的磁调制式直流电流比较仪(DC current comparator,DCC)和具有光纤数字同步的电子式DCCT校验仪。重点对标准器和校验仪进行了现场抗干扰分析,对于标准器现场使用时可能遇到的母线偏心和邻近通流导体干扰情况进行仿真分析,优化磁屏蔽结构,研制了DCC样机,经中国计量科学研究院校准,该DCC不确定度为5×10-6,在此基础上进行了母线偏心和邻近导体影响测试,验证了优化的屏蔽结构能够有效抵御现场干扰;为检验校准系统,采用0.2级DCCT进行了校准测试,结果表明校准系统不确定度优于5×10-4。